DIFFERENTIAL SURVIVAL OF ALBUMIN IN ANCIENT BONE

The identification of blood proteins in ancient bone is important (1) because detection of simple proteins can give information on species s pecificity and evolution, and (2) because the methods used provide a s ound technical basis for investigating the survival of more informativ e proteins, such as HLA and blood groups, which would shed light on ge netic profiles and disease predispositions of ancient populations. Our previous studies used a sensitive and specific enzyme-linked immunoso rbent assay (ELISA) with monoclonal antibodies and showed that albumin can be identified in human skeletal remains at least 4000 years old. However, the factors which affect survival and diagenesis of proteins within ancient bone remain largely unresolved. In the present studies, the results obtained after testing extracts of ancient bovine and hum an bone for albumin with the ELISA have been compared. The human extra cts were prepared from intact (''closed'') vertebrae from formal buria l sites. Well-preserved bovine material, on the other hand, could not easily be found and most of the bovine extracts had to be prepared fro m assemblages of bone which were ''open'' (i.e. the spongy interior wa s exposed), either because of butchering or weathering. Although album in could be detected in both bovine and human bones which were several thousand years old, the survival pattern between the species was stri kingly different (chi-square = 11.7, P<0.001); albumin was identified in 23 of the 31 human extracts but in only two of the 14 bovine ones. The assay for bovine albumin was as sensitive as that for human albumi n and had been equally successful in identifying blood stains on burie d samples of gauze. As part of the present studies, a modern experimen t was also performed in which ''open'' fragments of bovine and human b one were buried in a suburban garden exposed to high rainfall and exhu med and tested at set intervals over a 26-month period. The results sh owed a pattern of albumin survival similar to that observed with the a ncient bovine bone, i.e. survival was much poorer than with the intact ''closed'' bone from the ancient human burials. It was concluded that bone integrity is of great importance for protein survival and that e xposure of marrow and trabecular bone to the physical and chemical eff ects of water is the most significant single factor in the production of diagenetic changes. In this respect, water appears to have a far gr eater effect than age, soil content, pH or heat.